Chip security shield blocks backside hacks

March 19, 2017 // By Peter Clarke
French research institute Leti (Grenoble, France) is proposing a low-cost way to protect chips form invasive and semi-invasive attacks through the backside of the chip.

These attacks take the form of infrared laser light, chemical delayering and scanning focused-ion beam to remove material and provide access to the integrated circuit. This access can then be used to gain design information and, potentially, access to data.

"Implementation of multiple hardware and software countermeasures is making integrated circuits more secure, but the backside of a chip is still considered to be vulnerable to physical attacks," said Alain Merle, Leti's marketing manager for security.

And so Leti is proposing a shield made of serpentine track in metal sandwiched between two polymers one being opaque to infrared and hiding the serpentine path. The interior polymer is designed to detect chemical attacks.

Schematic internal view of the backside shield of a secure IC. Source: Leti.

The protection comes from the resistance along the length of the serpentine trace or multiple serpentine traces which covers the whole of the back face of the die. Any activity that alters the serpentine trace changes the resistance which could be used as a trigger to delete sensitive data.

Because these are standard packaging processes they provide hardware security with only a few additional steps and at low additional cost, Leti said.

Leti's research results will be presented at this week's Device Packaging Conference in Fountain Hills, Arizona, in a paper entitled "Backside Shield against Physical Attacks for Secure ICs."

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